hehe ive been making this suggestion a lot lately. cant hurt to go at it again.
strap a fan to your card. on the outside. make sure it directs air into the hole that your gpu fan is in. make sure it directs air in the same direction. i crazy glued a casefan to a dying 8800gts, it now runs cooler and overclocks better than it EVER did before. its not pretty, but its effective. the higher rpm the fan you add on, the better.
http://www.overclock.net/gallery/data/500/medium/PB190021.JPG
something like that, tho it doesnt have to be quite so ugly. mine looks considerably better. ^^
*edit* scratch that, i just noticed your videocard doesnt have a sheath. (a plastic cover.)